1. The Field of the Invention
This invention relates to systems, methods, and apparatus for communicating detonation and control signals in a perforating gun assembly.
2. Background and Relevant Art
During oil or gas extraction operations, a well casing, including the surrounding cement layers, can be perforated to access particular areas or zones of oil and/or gas deposits. Particularly, such perforations can create flow conduits, which can channel oil and gas from the deposit areas into the well. In some instances, a hydraulic fluid can be pumped into the well and through the perforations to produce fracking (or hydraulic fracturing) in the surrounding rock layers, which can facilitate increased flow of oil and/or gas into the well.
Commonly, the perforations are made with a perforating gun (or a perforating gun assembly) that is loaded with explosive charges (e.g., shape charges). Such perforating gun can have multiple charges positioned about the circumference thereof. Accordingly, as the perforating gun fires or detonates the charges, resulting blasts can create perforations at multiple locations about the circumference of the well casing.
A perforating string incorporating a single or multiple perforating guns can be lowered into the well and the perforating guns can be positioned at desired depths. Subsequently, a detonation signal from a detonation controller (typically located at ground level) can be sent to the perforating gun, detonating the charges in a desired sequence. For instance, the perforating string may contain two perforating guns, and the lower perforating gun may be fired first, while the upper perforating gun can be fired thereafter.
Commonly, zones that contain desirable amounts of oil and/or gas deposits can be relatively thin but numerous. Such zones can be separated from each other by nonproductive sections. Hence, using a perforating string with multiple perforating guns can be a most efficient procedure for accessing the oil and gas deposits near the well. Moreover, to access the oil and/or gas deposits, the multiple perforating guns can be selectively fired, to perforate the well casing adjacent the desired zones.
In some instances, the signal from the surface passes through a connection switch and triggers a detonator. The detonator can then ignite a detonating cord (e.g., Primacord), which can, in turn, detonate the explosive charges of the perforating gun. Commonly, connection switches, which pass the signal from the surface to the detonator, have various moving, mechanical components. Such mechanical components can increase the risk of failure of the connection switch. For example, connection switches can be subjected to high pressures (e.g., static pressure within the well and increased pressure from a blast wave created after detonation of the explosive charges) and high temperatures.
If a connection switch fails, usually the entire perforating string, including all of the perforating guns, is withdrawn out of the well to remedy the failure. Because some of the perforating guns may contain undetonated explosive charges extreme precautions typically must be taken to avoid surface detonation. Furthermore, usually, to replace the failed connection switches, the perforating guns are disassembled, which can be dangerous, time consuming, and expensive.
Accordingly, there are a number of disadvantages in devices, systems, and methods for communicating detonation signals in perforating gun assemblies that can be addressed.